the correction of astigmatism in cataract and refractive surgery

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  • World Ophthalmology Congress 2012 | 16 20 February | Abu Dhabi

    Tackling ROPThe KIDROP-experience shows that tele-ophthalmology is a cost effective possibility to spread ROP-screening programmes into the ural areas of India. ( Page 3

    Therapies for AMDNoumerous new medical therapies for wet age-related macular degeneration are under investigation. This is one of the most rapidly evolving fields in oph-thalmology. ( Page 8

    Tears and BubblesFemtosecond laser flap complications are very rare and often linked to the surgical technique. Usually they can be handled without consequences for the patient. ( Page 11

    World Ophthalmology News

    An Enriching ExperienceThe World Ophthalmology Congress 2012 in Abu Dhabi: Outstanding Speakers, Ultra-Modern Exhibition Centre, Traditional Hospitality

    ABU DHABI [jp] For the first time the World Ophthalmology Congress (WOC) will be hosted in the Middle East and Africa Region.

    T he destination is definitely new to most of the participants of ophthalmic congresses: Abu Dhabi, the capital of the United Arab Emirates (UAE) will be the heart of the ophthalmic world from 16 to 20 February 2012. Never before such a prestigious international medical meeting has taken place in the Middle East and Africa Region.

    Another World-Class CongressDr. Abdulaziz AlRajhi, this years congress president, is confident, that the WOC 2012 will prove to be an enriching experience to all the parti-cipants and delegates. High quality scientific content from more than 2000 internationally recognized speakers, a rapidly evolving city with an ultra modern exhibition centre and the unique Arab culture: These are the elements that will contribute to a high standard congress. Dr. Bruce

    E. Spivey, president of the Interna-tional Council of Ophthalmology is sure: You can expect another world-class congress, matching those in Ber-lin, Hong Kong and Sao Paulo.

    Chairman of the scientific pro-gramme is Prof. Dr. Peter Wiedemann who coordinates a programme that will cover 35 subspecialty and topic

    areas. More than 45 sessions will be organized by the International Council of Ophthalmology members and par-ticipating societies. Symposia, case studies, debates, panel discussions, video sessions and interactive lectures will give every congress attendee the possibility to gain insight into the latest developments in their respecitve

    topic. Leading ophthalmologists around the world will coordinate, moderate oder chair the sessions.

    Ideal SettingWiedemann encourages the colleagues from all over the world to attend the WOC 2012: A modern city combined with a rich cultural

    heritage, Abu Dhabi promises to be an ideal setting for scientific communi-cation and innovation.

    See, Hear and Taste the CultureThe local organizers as well as repre-sentatives of the Abu Dhabi Tourism Authority also recognize the congress as an opportunity to present the capital of the United Arab Emirates and the wider emirate to a worldwide audience. Members of the Middle East Africa Council of Ophthalmology (MEACO) strive to ensure that all WOC visitors experience a stimulation envi-ronment. Prince Abdulaziz Ahmed Abdulaziz Al Saud, chairman of the MEACO board, promises culturally rich social events: You will see, hear and taste the unique Arabian culture.

    Luxury and StyleA great opportunity to do so will be the cultural night on 17 February at the Abu Dhabi Emirates Palace: Luxury and style, infused with tradi-tional values of hospitality and respect will be the source of a memorable experience. W

    Dealing with Small PupilsMechanical Stretch, Iris Hooks, Malyugin Ring

    SUNDERLAND The definition of a small pupil depends on the degree of ex- perience of the surgeon, and also on the degree of surgical difficulty expected to be encountered.

    A n experienced surgeon may be happy to operate with a 3-4 mm pupil in a straight-forward case, but may be unhappy with a 4.5 mm pupil if dealing with a rock hard cataract. The problems caused by a small pupil are not con-fined to difficulties removing the nucleus without damaging the iris margin. A smaller pupil allows less light to enter the eye, and so the red reflex may be poorer with smaller pupils and the threshold for use of a capsule staining dye is therefore lowered.

    Small pupils may be due to poste-rior synechiae from previous inflam-mation or previous miotic use (rare now but was common in the past). The condition may in other cases be due to some other concurrent disease/medi-cation e.g. pseudoexfoliation, tamsu-

    losin use, or it may simply be a small pupil.

    Always check to see if there are posterior synechiae and carefully break these (including at mid-stroma if patient has been on long term miotic).

    Simple mechanical pupil stretch with 2 instruments can be effective in many cases (figure 1). It is important to stretch by taking the instruments almost into the angle. One problem is that the pupil may then re-constrict or wave in the breeze because of multiple sphincter rupture.

    Experience with IFIS from tamsu-losin use has shown the value of intra-cameral alpha agonists either at the outset or during surgery. We favour phenylephrine diluted in BSS (others advocate epinephrine). The contents

    of 1 minim of 2.5% phenylephrine (Bausch & Lomb) added to 1-2 mL of BSS injected into the AC can give added dilatation, and certainly dimi-nishes or prevents re-constriction and also prevents iris prolapse.

    In all cases consider reducing your fluidics parameters. A high aspiration flow rate increases the risk that you will aspirate the pupil margin in small pupil cases. A high vacuum then makes it much more likely that you will damage the iris tissue if you do catch it, and this can cause problems for the surgery and problems for the patient afterwards.

    For some cases it is desirable to mechanically dilate and then in some way to fix the pupil. We initially learned from vitreo-retinal surgeons to use iris hooks. If you use iris hooks

    ensure that your incisions in the cornea to place the hooks are very peripheral (there should be bleeding at each incision) and horizontal (figure 2). This ensures that you are pulling the pupil margin peripherally rather than upwards.

    Some hooks come in packs of 5 the 5th one is meant as a spare in case you drop one. However, you can also plan to use 5. When using 4 make a diamond pattern rather than a square in other words one hook should be placed under the incision so that you get maximum retraction where you are entering the eye with the phaco tip (figure 3). Try to space the incisions/hooks as symmetrically as possible.

    continued on page 2 (

    ADN

    ECThe heart of the ophthalmic world from 16 to 20 February: The Abu Dhabi National Exhibition Center

    David Allen

  • WOrld OphthalmOlOgy NeWs | 20122 | WoC 2012

    Current Status of Phakic IOLDoubts are Justified but New Lenses Arouse Expectations

    FRANKFURT Endothelial cell loss or iatrogenic cataract discourage many surgeons from using phakic lenses. New, modern PIOL may offer new solutions to their questions.

    T rials comparing corneal refrac-tive surgery with phakic intraocular lenses (PIOL) reveal the superiority of the latter in terms of quality of vision, while other para-meters like stability, safety and effi-

    cacy are comparable.1,2 However, PIOL today are most often used in patients, for whom refractive corneal surgery is not applicable due to high ametropia, large pupils and thin or irregular corneas. Known severe long-term complications like the endothelial cell loss or cataracts discourage many surgeons from using phakic lenses as an equal procedure next to laser refractive surgery.3,4

    The question arises, whether these doubts, resulting from many failures

    in the development of different PIOLs, are still appropriate when modern PIOL are used? The answer is yes. And no. Doubts are justified, but the nega-tive experiences with former implants are not 100% applicable to todays lenses.

    The most dreaded complication of posterior chamber PIOL is iatrogenic cataract, induced by contact between the PIOL and the natural lens due to insufficient vaulting and/or modified aqueous humour fluidics. Schmi-dinger et al5 show a nearly linear and continuous decrease in the distance of the ICL V4 (STAAR) and the natural lens in 84 patients. From 466218 m directly after surgery the distance decreases to 184159 m after 74.123.1 months. The resulting clinical significant anterior subcap-sular cataract rate in their retro-spective trial cohort was 28% after 44 months. 17% of the patients under-went explantation of the PIOL follow-ing cataract surgery. Inadequate clear-ance between the natural lens and the PIOL was a significant predictor for anterior subcapsular cataract forma-tion. The latest design evaluation of the ICL provides a central hole in the optic to prevent pupil-lary blocking and to enhance the aqueous humour fluidics in the gap between the ICL and the lens to reduce cataract formation. (Figure 1) First results by Shimizu et al6 show very good short-term visual results, compa-rable to other phakic lenses, proving the optical practicability of the central hole. Although this is a very promising implant, longer follow ups are needed to evaluate the cataract rate and long term vaulting stability.

    In opposite to this very new poste-rior chamber PIOL, the long-term results of todays most commonly used anterior chamber iris-fixated PIOL (Artisan, Ophthec, figure 2) are well known. The visual outcomes are excellent, even in toric patients. Sizing of the implants is, contrary to posterior chamber or angle-supported anterior chamber IOL, not an issue.

    The weak point of iris-fixated PIOL is the endothelial cell loss. Studies show mean rates of

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